Musannaf Ibn Abi Shaybah 29709 — A man who finds a man with his wife

Yahya bin Sa'id said that Sa'id bin al-Musayyib said: A man from the people of Syria named Ibn Khaybari found a man with his wife, and he killed his wife, or killed them both. The matter was presented to Sayyiduna Mu'awiyah (may Allah be pleased with him), and ruling on it became difficult for him. He wrote to Sayyiduna Abu Musa (may Allah be pleased with him) to ask Sayyiduna Ali (may Allah be pleased with him) about it. So Sayyiduna Abu Musa asked Sayyiduna Ali, and he said: Indeed, this matter has not occurred in our land; I adjure you to tell me about it. So Sayyiduna Abu Musa told him about it. Then Sayyiduna Ali said: I am Abu Hasan: if he does not bring four witnesses, then you are to hand him over completely.